Adding zoom lense to projector

I'm looking at commercial projectors (for my own sanity), but I've run into a problem. The room where I will have the projector requires a 19 foot distance b/w the projector and the screen. The projector I'm looking at (Canon LVS1: can project a clear, bright image this distance, but the image is WAY too large. (~130", and I want 60").

This projector has threading on the is it possible to use a camera zoom lense (similar to to make the image smaller? (assuming I can match the threading)

If I do use a standard lense will that distort the image?

What if I can't find a threading match, can a lense (or series of lenses) mounted in front of the projector do the trick?

Maybe I'll just have to go buy one and try it out...but I'd rather have some educated guesses from the DIY crowd before I go and spend cash.

Thanks for the info,
ya know, i dont see why not. ive been mulling it over since you posted this, and i think its a good idea... it may work. the only problem is many lense assemblies (such as a camera lens for instance) have other lenses build in, and are designed for a fixed focal point. so, maybe that wouldnt work, i dont know a WHOLE lot about camera lenses. as far as threading is concerned, i know there are a ton of converters, upsizers, downsizers, etc, at camera shots or whatever that might work... my camcorder has a 37mm threading, but with an adapter, i can put my filters on it from my 46mm regular camera...

but logistically, i dont see why it wouldnt work. its all light, its all optics.